Freds note just reminded me, I was once on a ship which had the water surface full of balls, they looked to me suspiciously like ping pong balls?I expect a smaller version of these would do the same job.RegardsJack

Now to find some sort of little plastic balls that can be thrown in a dish washer periodically without them disappearing down the drain. The size of marbles might work. They would let the float move freely.

Barbara has a small mesh bag that she uses to keep her more delicate items from getting eaten by the clothes washer. I could confine them in one of those for cleaning.

And now to find black ones so as to avoid comment from unsophisticated observers. Ones with images of cartoon coyotes and road runners probably won't do.

Mike, I've been thinking about this a bit. Ping Pong balls are very light for there size which makes them very buoyant. I don't think a floating layer of them would cover much water surface. The balls Fred is referring to are probably much heavier to where they submerge near their equator to cover as much surface as possible. Would probably be better to go to a toy store and get small foam rubber balls like the type used for paddle balls. They are much heavier.

So now, all you mechanical engineers out there, how deep does a sphere with a specific gravity float? I've done this once with rectangular solids as an exercise in how a board will float, either flat or on edge or at an angle. But I can't find my work sheets and don't care if the ball floats upside down (grin). I just want to know whether it will bob on top or almost sink.

Calculate the volume in square inches, then calculate the weight of water of equal volume, then compare the weight of the sphere, ideally it should be half the weight of the water.

-Ron

While working earlier, I was thinking about this more. Oil in the hot well is an issue, and removing it is a big one too. I think if there were a buoyant partially submerged plate with a conical bottom and at the apex of this internal shallow cone a standpipe through and above the plate was fitted, oil would be pushed up it. Water seeks it's own level, but oil and water do not seek equal level. Would have to compare the specific weight of each, but it might work. Have a gate at the bottom of the standpipe and a small valve to drain it.

In the case of those Poly spheres the specific gravity is a given (.91) so I should be able to short circuit much of the calculations and assume that it will float 91% immersed. I'm sure there is some major flaw in my reasoning.

If my thinking is correct, though, I need spheres with a specific gravity of .5 and so far I haven't found any impervious materials that are near that.

Love these practically useless speculations.

If I were serious about sealing the water surface from the air I would have a good fitting floating panel on the surface that had a link to the float arm. Get rid of the cylindrical brass float. Too simple, I know. And it might catch and bind on the sides of the well.

As to oil, I don't lubricate my engine internally so all I am filtering for is particulates. I get a year out of a couple of hunks of Oilsorb wrapped around the suction lines to the engine pump and the hand pump.

I have sipped some of the water from the hot well and it seems to be fairly free of air as it tastes very 'flat'.

As a matter of minor interest, my present boat has a miniscule hotwell: it's roughly a cube of very neatly soldered brass plates, just under 6" across. She also has a feed-water heater composed of an array of pipe bolted to the un-insulated end casing of the modified Yarrow type boiler. I have no real experience myself of how well it works yet, but it certainly has performed well (for others) for at least the last ten years.

The pipework into my little hotwell is slightly complex, namely: 1. Outlet to main eccentric driven feed pump 2. Outlet from air pump(i.e. the usual ones, but then:) 3. Outlet from the whistle and Windermere kettle steam line 4. Outlet for the air pump when running in reverse (It's a vane type) 5. Air/steam bleed from the top of the feed water heater.

The engine has a multi-way lubricator - 11 ways although one is blanked - with flexible tubing to the crossheads. One of the ways goes to the high pressure valve chamber (balanced slide valve), but it has an extra needle valve to restrict internal engine oil to drips per hour. There's a drain valve from the bottom of the valve chamber, which gets opened along with cylinder cocks when warming up, and what comes out of it before my test steamings has been a bit oily.

I rather suspect any engine which runs with a drop of internal oil will normally work with an oil film on the surface of the hotwell, which will restrict any transfer of oxygen in or out, making some of the earlier discussion redundant. Without being certain, I would have thought that a close-fitting lid would have resulted in saturated water vapour above any hotwell surface, and not much air.

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